Switching apparatus for telephone-exchanges



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ATENT JOSEPH P. DAVIS, OF NEW YORK, N. Y., ASSIGNOR TO THE AMERICAN BELLTELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

SWITCHING APPARATUS FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 559,367, dated May 5,1896.

Application led August l0, 1895. Serial No. 558,821. (No model.)

To @ZZ whom it may concern.:

Be it known that I, JOSEPH P. DAVIS, residing at New York, in the countyof New York and State of New York, have invented certain Improvements inSwitching Apparatus for Telephone-Exchanges, of which the following is aspecification.

My invention concerns switching apparatus of telephone-exchanges, beinga device for permitting the subscriber to designate to an attendant at acentral station a particular group of subscribers among which thedesired correspondent may be found. In exchange systems comprisingseveral oiiices in which subscribers lines center, the subscriber maythus designate the particular office in which the required lineterminates, the call being immediately trunked to an operator at theofiice indicated.

This invention contemplates the use, with a switching system comprisingan annunciator or receiving-board in which the subscribers lineterminates in a signaling instrument, several switchboards, eachcontaining terminal connection-sockets of a different group of lines,and office trunk-lines extending from the annunciator-board to theswitchboards, of a signaling instrument or indicator for each-line atthe annunciator-board controlled from the substation, whereby thesubscriber may indicate to the attendant at the annunciator-board theswitchboard at which the line required terminates. This signaling devicemay be any of the well-known contrivances for designating a particularone of several requirements by the display or actuation of an indicatorby mechanism controlled at the distant station. A form of the Vheatstonedial-telegraph is perfectly suitable for use in the present invention.

This improved-switching system is illusi trated in the accompanyingdrawing, in which a number of subscribers7 lines are representedconnected with the switching apparatus of the exchange-offices.

The drawing shows only three of the sub-` scribers lines as beingprovided with indicators and connection-sockets upon anannunciator-board as sufficient for purposes of explanation, it beingobvious that the other lines represented on the drawing may be providedwith similar indicators and connections at the same annunciator-board orat another but similar one.

There are in the exchange system here shown three switchboards A, B, andO, which may be assumed to be located at different ofiices, and anannunciator-board D, which may be in the same office with switchboard A.The three substations E, F, and G are equipped with transmittinginstruments of the dial-telegraph, represented in the drawing by thedial andv index only.` These stations are connected by lines l, 2, and3, each with a connection -socket d and a dial-receiving instrument cl2in the annunciatorboard D and each with a connection-socket d in theswitchboard A. Lines 4. and 5 from substations I'I and I lead each to aconnection-socket b in switchboard B, and lines 6 and 7 to connectionsockets c in switchboard O.

One or more interoflice trunk-lines, 8, extends from annunciator-board Dto switchboard A, terminating in the usual plugs m, and m2 for makingconnection with the sockets. Another trunk, 9, extends from board D toswitchboard B, and still another, l0, from the annunciator-board toswitchboard C. These trunk-lines may be equipped with any of thewell-known devices for informing the operator at the switchboards,automatically or otherwise, when connection is made with the trunk-lineat the annunciator-board and for signaling to the switchman at thelatter board the disconnection of the trunk-line at the switchboard. Theswitchboards are supposed to be furnished with the usual telephones,calling apparatus, and keys for the use of the operators in establishingconnection with the lines.

In operating this system the subscriber must know what group or officeforms the terminal of the station with which he wishes to communicate.Suppose, for example, the subscriber at station E should wish to havehis line connected with line to station I'I. He will have informationthat station H belongs to group or ofiice B. I-Ie will place the indexof his transmitting instrument at B, whereby IOO 2 was@ the index of thecorresponding receiving instrument d2 in annunciator-board D Will becaused to indicate B. At this signal the attendant switchman Will insertinto the springjack d of the same line the terminal plug m of thetrunk-line 9, extending to switchboard B. The operator at switchboard oroffice B,

having received information that the line of a calling subscriber hasbeen connected with trunk-line 9, will bring her telephone into circuitwith that trunk-line, learn from the subscriber the number of theparticular line with which connection is desired, and perform therequired switching in the usual Way.

If the calling subscriber should require connection with a member of thesame group with himself, he would turn the index of histransmitting-dial to A to indicate to the switchlnan that the callshould be trunked to switchboard A, or if he should requirecommunication With station K or L he would turn the index to C, knowingthat these lines terminated at switchboard C.

I claim as new and desire to secure by Letters Patent- 1. Incombination, several telephone-lines extending to terminalconnection-sockets, an indicator for one of the lines adapted toindicate any of several objects, means for controlling the indicatorfrom the substation of the line, and switching apparatus for makingconnection from the socket of the line having the indicator to theterminal socket of any other line, as described.

2. In combination, several telephone-lines terminating inconnection-sockets on dierent switchboards, an indicator adapted toindicate any of several objects for one of the lines in anannunciator-board and means for phone-lines terminating inconnection-sockets in different sWitchboards, trunk-lines eX- tendingfrom the annunciator-board to eachswitchboard, and switching apparatusat the annunciator-board and at the switchboards for making connectionbetween any trunkline and any socket, as described.

In testimony whereof I have signed my name to this specication, in thepresence of two subscribing witnesses, this 5th day of August, 1895.

JOS. P. DAVIS.

lVitnesses:

GEO. WILLIS PIERCE, FRANK C. LocKWooD.

